1. Field of the Invention
The present invention is related to a backlight module, and more particularly, to a backlight module using a connector with voltage-conversion function or a step-up module with signal transmitting function.
2. Description of the Prior Art
Liquid crystal display (LCD) devices, characterized in low radiation, small size and low power consumption, have gradually replaced traditional cathode ray tube displays (CRTs) and been widely used in electronic devices, such as notebook computers, personal digital assistants (PDAs), flat-panel televisions or mobile phones. As a key component in the LCD device, the backlight module is normally disposed directly underneath the LCD panel or along the sides at the rear of the LCD panel. Using lamps and various optical devices (such as diffusion plates or prisms), high-luminous and uniform light source can be provided.
The basic operation of the backlight module is to provide an output signal for driving the lamps according to an input signal. The input signal is provided by the direct-current (DC) power transmitted from the driving circuit of the LCD device, and its initial voltage level is insufficient for driving the lamps. Therefore, voltage-conversion is performed by the step-up circuit of the inverter, thereby generating the high-voltage signal for driving the lamps. The inverter is disposed on a printed circuit board (PCB). In order for the inverter to transmit the high-voltage signal to the lamps, the lamp electrodes, the connector and high-voltage wires are welded on the PCB, which makes the assembly process very time- and effort-consuming.
Referring to FIG. 1, which is a diagram illustrating a prior art backlight module 10. The backlight module 10 includes an inverter 110, a lamp set 120, and a socket-type connector 100. The inverter 110 includes a control circuit 112, a power converter 114 and a step-up device 116. The control circuit 112 can generate a control signal VS corresponding to each lamp in the lamp set 220 according to a DC signal VDC transmitted from the driving circuit of the LCD device. The power converter 114 can output a symmetrical low-voltage variable duty signal VDUTY by converting the DC signal VDC, whose voltage level and vibration amplitude are then enhanced by the step-up device 116 in order to output a corresponding high-voltage signal VLAMP. When assembling the backlight module 10, the inverter 110 and the lamp set 120 can be directly inserted into the slots of the socket-type connector 100 so that the high-voltage signal VLAMP generated by the inverter 110 can be transmitted to the lamp set 120.
Compared to the traditional welding technique, the prior art socket-type connector 100 enhances the efficiency of the assembly process. However, assembly personnel face the danger of contacting the high-voltage output end of the inverter 110. To prevent deadly electric shock, high-voltage insulating structure needs to be adopted, which requires large-size PCB. Also, the inverter 110 needs to include the step-up device 116 for voltage-conversion, which also occupies large space. Therefore, the prior art socket-type connector 100 fails to meet the demands when developing thinner LCD devices.